Stackable chairs are widely used in institutional and commercial settings of all sorts, such as meeting and conference rooms, auditoriums, multi-purpose assembly halls, and gymnasiums that can be temporarily converted to auditoriums. Stackable chairs occupy a small volume for storage, thus making space in a room available for other purposes.
Most stacking chairs have a fixed backrest, which is comfortable for one sitting posture but uncomfortable for sitting postures other than the one for which it is designed. A chair occupant quickly becomes fatigued if he or she does not change his or her sitting posture from time to time. Chairs with fixed backrests, therefore, are uncomfortable for significant amounts of time for most users.
Stacking chairs commonly have fixed seats. Rows of chairs with fixed seats have to be relative widely spaced in order to allow people to pass easily along the aisles between the rows. Wider spacing of rows reduces the seating capacity for any given space.
An object of the present invention is to provide a stackable chair that is comfortable to sit on in many seating postures, attractive in appearance, highly durable, versatile in use, and economical to produce. A further object is to provide a stackable chair that can be easily and quickly assembled by unskilled assemblers using simple tools, thereby permitting the chair to be shipped in disassembled condition to a point of sale or end use. It is also desired that a stackable chair have a limited number of components that can be used interchangeably to suit the desires and needs of the end user. Still another object is to permit stackable chairs to be arranged in closely spaced rows for high density seating.
The foregoing objects are attained, in accordance with the present invention, by a chair having a frame that includes a crosspiece, a front leg, a rear leg and a backrest support attached to each end of the crosspiece, a seat mounted on the crosspiece, a backrest, and a pair of backrest-mounting mechanisms mounting the backrest on the backrest supports for pivotal movement about a horizontal pivot axis between an upright and a rearwardly inclined position. Each backrest-mounting mechanism attaches one side of the backrest to the backrest support and includes a pivot pin attaching the backrest to the backrest support for pivotal movement, a spring engaged between the backrest and the backrest support and biasing the backrest to an upright position, and a stop pin affixed to one of the backrest and the backrest support and received in a stop groove in the other of the backrest and the backrest support. The stop pin is engageable with end stop surfaces of the stop groove so as to limit the range of pivotal movement of the backrest and establish the upright and inclined positions of the backrest.
As is well-known per se, the mounting of a backrest of a chair for pivotal movement enables the backrest to assume any position between upright and significantly tilted back in response to the forces applied to it by the anatomical back of a person sitting in the chair so as to comfortably support the sitter""s back. The backrest mounting members of a chair embodying the present invention is of simple construction, easily installed, inexpensive, durable, and requires little space. Advantageously, the spring is a coil torsion spring having a coil and projecting leg at each end of the coil, the coil being received around the pivot pin, one leg being received in a cavity in the backrest and the other leg being received in a cavity in the backrest support. In addition, the cavity in the backrest is in a laterally outwardly facing surface of the backrest and the cavity in the backrest support is in an inwardly facing surface of the backrest support abreast of the outwardly facing surface of the backrest support. Thus, the backrest mounting member is concealed from view.
It is preferred for the stop pin to be affixed to the backrest and the stop groove to be formed in the backrest support. The groove requires more space than the stop pin and is best provided in the backrest support, whereas the stop pin is readily supported in the backrest without requiring undue enlargement of the region of installation. To facilitate installation of the stop pin, the backrest support has a hole opening into the stop groove and aligned with a hole in the backrest that receives the stop pin so that the stop pin can be installed from the lateral (outer) side of the backrest support.
In preferred embodiments of a chair according to the present invention, the seat is affixed to a pair of laterally spaced-apart seat supports mounted on the crosspiece. The seat supports may be affixed to the crosspiece or they may be pivotally mounted on the crosspiece so that the seat can be tilted up. In advantageous constructions, the crosspiece is tubular, and at least the front leg and the backrest support at each end of the crosspiece are portions of a monolithic casting of a metal, preferably aluminum. Each casting includes an integral mounting boss that is received within an end portion of the crosspiece. The mounting boss of each casting extends endwise into and is affixed within the crosspiece by a connector pin that extends through mating holes in the crosspiece and the mounting boss. Such an arrangement facilitates manufacture and assembly of the chair frame, uses space efficiently, and is strong. Each casting may also include the rear leg. It is also possible, however, to have separate rear legs and attach them to the castings that include the front legs and the back supports. It is desirable for the mounting boss of each casting to include an axial rib that is received within a slot in the crosspiece so as to attain the proper rotational positioning of the boss in the crosspiece and further affix the casting to the crosspiece against rotation.
In addition to affixing the frame casting to the crosspiece, the connector pin preferably retains the corresponding seat support seat in the proper axial position on the crosspiece and serves as a stop for setting the down and tilted up positions of the seat. To those ends, the connector pin extends completely through the crosspiece and includes portions projecting outwardly from opposite sides of the crosspiece. The projecting portions are received in stop slots in the seat support, are in sliding engagement with side surfaces of the stop slots to retain the seat support on the crosspiece against lateral movement (axially along the crosspiece) and are engageable with end stop surfaces of the stop slots so as to establish the up and down positions of the seat supports. The affixation of each frame casting and seat support and the stop function for the seat tilt-up feature are accomplished with a single elementxe2x80x94the connector pinxe2x80x94which is inexpensive, occupies little space and is easily installed.
Many users of chairs embodying the invention will be content to have chairs in which the seat is tilted up and down manually. Other users will find it to be desirable for the seat to tilt up automatically whenever no one is sitting in it, thus leaving aisles between rows of chairs free of obstruction by seats left tilted down. The latter users"" wishes are fulfilled, according to another aspect of the present invention, by coupling a spring between the crosspiece and at least onexe2x80x94and preferably bothxe2x80x94of the seat supports to bias the seat to pivot to the tilted-up position. For example, a simple tension coil spring coupled between the connector pin and the seat support can be provided to bias the seat to the tilted up position.
The chairs of the present invention are designed to be stacked with the seat in the down position. To facilitate stacking of chairs with automatic seat-tilting arrangements, one of the seat supports may be provided with a lock pin mechanism for locking the seat in a down position. In an advantageous design the lock pin is normally held extended by a spring in a release position. The lock pin may be received in a tubular boss on a flange portion of the seat support and be movable into a hole in the crosspiece to lock the seat in a down position. The forces of the seat tilt-up springs on the seat supports act through the lock pin, which is thereby captured by friction in the hole in the crosspiece. With such a construction of the lock pin mechanism, a downward force on the seat eliminates the friction engagement of the lock pin, which pops out and releases the seat so that it automatically tilts up.